Work holder



T. E. MEAD,

Feb. 8, 1949.

WORK HOLDER Filed June 18, 1945 Patented Feb. 8, 1949 PAT WORK HOLDER Theodore E. Mead, Wilmette, "Ill., assignor to Mead Specialties Company, Inc.,;a corporation 7 of Illinois Application June 18, 1945 Serial No. 600,156 V This invention relates to a work holder, and more particularly to power driven apparatus for holding a work-piece during a machining operation.

An object of the invention is to provide a work holder in which the parts are adjustable for varyingthe extent of the stroke in applying the desire pressure while at the same time permitting the removal of the collet and the substitution of a new collet therefor. A further object is to provide friction means whereby the collet may be adjusted manually to the desired point and which willprevent the collet from turning after it hasbeen adjusted to suit the work in hand. Other specific objects and advantages will appear as. the specification proceeds.

Theinvention is illustrated in a preferred embodiment, by the accompanying drawing, in which-- Figure 1 is a vertical sectional view of apparatus embodying my invention; Fig. 2, a transverse sectional view; and Fig. 3, a top plan view of a friction. spring employed. 7

The work holder preferably comprises a. base in having a depending flange portion I l which rests upon a work table. The base may be secured to the work table, if desired, by any suitable means, such as screws or the like, passing through the base and into the table. Above the base a main body is mounted, including an enlarged cylindrical portion I2 formed with a cylindrical bore [3 and having a tubular extension M of reduced diameter extending upwardly therefrom. The extension It carries at its upper end a clamping ring having a conical central bore therein.

' Within the bore l3 there is slidably mounted a piston it which is formed with a tubular neck I1 fitting slidably in the extension M. The piston carries apacking I8 working against the inner surface of the bore IS. A similar packing I9 is connected to the body 12 to seal around the neck ll of the piston. Preferably, an oil ring or like packing 2| is provided on the neck I! to prevent leakage of oil around the neck into the bore.

A collet or clamping member 22 is secured in the neck and is formed with a pluralityof jaws having conical outer surfaces indicated at 23 to cooperate with the clamping ring Hi. The clamping jaws are provided by'forming slots 22 in the hollow metal piece comprising the clamping member 22. The clamping member is screwthreaded to the piston at the lower end of the neck and is adapted to be raised by rotation of V the collet. The collet is hollow and is adapted to receive a work-piece at its upper end which will be securely clamped in position when the collet is moved down into the ring l5. A spring ring 24, having a lug 3'! bent inward to engage the keyway 38 of the collet 22, presses outward against "thewall ll of the neck ll, the frictionthus 4 Claims. (01. 279-4) caused preventing the collet from turning after it, has been adjusted to suit the work in hand. The neckl'l is preferably enlarged at ll, as shown moreclearly in Fig. l, to receive the spring 24.

In order to limit movement of a work-piece into the clamping member, a stop rod 25 is provided which extendsloosely into the clampingmember and is adapted to rest atits lowerend onthe work table. 1 The stop rod-may be of any desiredlengthto permit movementoi a' work-piece into.-the clamping, member to (the desired distance so that the yertical position of the work-piece in.. the holder will be accurately determined. r The stop rod may alsobe utilizedyaccordingto the invention, ,to, eject a completed work-piece from the clampingmember. For this. purpose, a collar. 26 is fixedjonthe; stop rodrand is engaged byone, end of a leaf spring v127 which is. rigidly attached to the under surface of the base at.it s opposite, end. The spring. yieldinglyiholdssthe stop rod down against the work table and permits it to be moved vupfor-ejecting the work-piece from the clampingmember. :r The rod is movedup by a'lever v28 pivotedintermediateits ends on a bracket 29 in the'base and having a forked end straddling the, stop rod-below the collar 26. The opposite end of thelever 28 is engaged by the end of 'a pistonrod 30 workingzon a cylinder 3|, as shown more clearlyiin my copending applicationSerial No. 517,640, filed January 10, 1944, for Workholder, now' Patent No; 2,428,496. Fluid pressure may be supplied to the cylinder 3| through suitable connections with a source of pressure.

The clamping member and a work-piece car: ried pthereby may be kept cleanand may be lubricated byproviding a constant flow of 1ubri-. cant through the clamping'member around .the work-piece during operation. For this purpose; the lower end of the neck I! is closed by a cover 33 which is rigidly attached to the piston and whichextends loosely through a central opening in the top of the base. Fluid, such as a lubri cant, can be supplied through a conduit 34 Such fluid will flow upwardly through the clamping memberaround the work-piece therein. to cool and lubricate the parts and to flush any chips therefrom. g I V Fluid pressure is admitted to the bore l3 above the piston l6 througha connection 35. Springs 36 are mounted upon base l0 below the piston l6 and serve to return the piston to its upper posi tion upon the release of pressure.

In theadjustment of the collet 22 by rotating the collet within the neck [1, it is extremely important that the collet be held firmly. in place after an accurate adjustment has been made. The friction spring 24, which lies within the en larged bore l1, maintains the colletins'uch-firm position. The spring is preferably locked to, the collet, 22 by bringing an inward] within a longitudinal groove 38 with which the collet is provided;

In the operation of "the device, is inserted in the collet or clamping member 22 and fluid is supplied to the space above the piston I6 through the connection 35. This forcesthe:

piston down so as to clamp the jaws of the clamping member inwardly into engagement withrthe a' work-piece work-piece to hold it securelyin'placeduringa machining operation.

On completion of the operation, when the pressurez-supplied mag-ethe ture byrrotatingit within the -threaded neck I12 This-maybe done manually 'or by anysuitable tool whichtengages thecollet 22. When the collet' has beentraised to the-desired elevation; itwill remain firmly in the adjusted position because'of th 'if1i0l7iOI1 spring .24 Since the key= 31 of- -the springs dssecurely lockedt the groove 38 of thei'col'letg the collet will' :not turn" from its adjustedi position without requiring the turning-of the spring 24. Thesdragieffect of "the spring is suilicientlyrgreat Lto rlprevent: such turning movementunlessrttheturning isdeliberate;

Itiwvillibe: seenthat any collet 22 i may beeunscrewed; and 'removed:from' the fixture," and anothericollet inserted; without I disturbing any other parts: of the.rfixture;-' and: without I the use ofitoolssz. Asisooniasthethreads at thebottom of th'ezcolletr 22 have: been: unscrewed p from the threads-.ain-- .the. :piston; :the; collet Lmay be liited out, leaving the spring 24 .insplace, ready to receivieand provideztorque-lresisting friction-for the nextzcolletito beinserted; V

Moreover, an infinitely fi'ne adjustment 2015 the coiletiis possible, resulting in aminimum length oftstroke for the piston l 6, thusreducin'g wearion moving parts: and :preventingcwaste ofpressure fluid i.Eurthermorepthis fine adjustment makes it :possibleito keep the leaves ior'jaws of the collet irn-tcontact' withzthe taperedwalls 'ofthe. ring atzall "times-preventing; chips from gettingbetween the bearing surfaces. lltihen properly adjusted; a:- vertical movement of only a few thousandth's ofa an inch is necessary for the collet torholdzior: to release the work-piece;

While :inthe'ioregoingspecification, I have set forthi certain specific structures as illustrative of thednvention; it will be understood that wide variation may bemade in such structure' for ac complishing the same result e without" departing from-the spirit of my invention;

I-tflaim-zi V 1.- Ida work holder, a casing providinga piston 1 chamber-andatubular bore aligned'th'erewithia piston insaid chamber and equippedwith -a-tuhu lar member received within said tubular bore; a" hollow clamping" member in"'saiditubu1ar*pis-. ton member and adjustably' connected thereto, means for admitting;- fluid to said-chamber to move said piston inone direction; means "as-: sociated with said casing for causing the clamp= ingmember to grip; a work-piece received;therein when said piston'is moved-insaid'directionby said' fluid; at least-one offsaid members'being equipped with a longitudinal key I slot"; and; a spring member equipped witharkey engaging said slot and having ;.arms engaging the mernbier- "to which; said spring is not attachedtby .saidfkey;

In a-"workholderr a casingmroviding a piss ton chamber and a tubular bore aligned therewith; a piston "in saids" chamber 2* and iequipped with arrupwardly-extendingtubular member extending into said tubular bore, a hollow clamping member in said bore threadedly connected to said piston-for longitudinal adjustment with respect thereto, at least one of said members being provide'd w-itha Vertical" slot, a key engaging said slot;=anda fr-iction-spring fixed to said key and having laterally-extending arms frictionally engaging'theamember to which said key is not attached, means for admitting fluid to said chamb'er'tomove said piston in one direction, and

means associated with said casing for causing saidclatmpingmemben to grip a work-piecei'received therein when said pistonvis moved tin-:said

direction-by said fluid, said frictionaspring ik'ey;

and vertical slot in said member releasably main-.1- taining said "clamping memben in: any: ofaiits adjusted positions relative to said-piston:

3. a-work holder; a :casing providingta.'pis ton chamber and a 1 tubular extension aligned therewith; a: piston in -saidchamber; a: colletr irr said' extensio'n threadedlyconnectedto said PiS-i ton for: longitudinal i adjustment withrespect thereto; said: collet zhaving a1: longitudinal slot therein; means: for admitting fluid; to sai'dfchams her to move said piston in ione-"directinm means associated with said casing -for:compressingizsaid clamping member iwhen said-piston .is movedsin said direction, a i key engagin z said iverticala slot in said collet, andiaspring fix'edto theaiouter surface of said key and having arm portions frictionally engagingthe 'casing;w-a1ls1about-isaid colletto normally resist-.rrotation xof saidicollet: said collet being rotatable against said resistance to adjust said collet-vertically 'withzrespectato.

saidapiston. a

49mm: work holder, a casingsproviding :arpisa ton-.chamberandta tubular bore'vertic'ally aligned therewith;a:clampingliringicarried.bysaidicasing above said tubular s'bore and having-inwardly tapered walls," a piston ill-1531C]. chambenz arcollet insaid tubular bore and havinginwardly-tapered walls engaging .theiwalis' ofssaid 'ringa said bullet having :slots therein sto .provide oclampings jaws and having also a threaded connection withisaid piston to a provide a for: vertical" adjustment rofi saidzcollet' withz respect 1 to. 5 aidepiston: said icol'let being: also provided with: a .sverticalguide :slotz'extenrling frorma central portion of th'ercolletidown to: the lower portion thereof; a key engaging:said guide slot, and.;a friction spring-i. fixed to rthe outer surface offsaid keyiandi'l'iaving:armsazens gagingrithe casing a aboutr'saidzcollet :tnormally'eto resist zrotation-sof' saidrjcoll'et:withrzrespect'to:said piston; andxmeans for admit-ting; pressure'ifiuld to said; fchamber above "saidapiston to zmove-ethei samedownwardly;

THEODORVEVEVP REFERENCES l CITED.

The;following:reierencessare .ofr-recordi-iuithe fila-of this: patent:

UNITED"'STATES" PATENTS 

